The measurement of mechanical behavior in very small samples, whose dimensions are on the order of microns and below, can offer advantages over conventional macroscopic testing in many instances. Motivations for investigating materials at this length scale include seeking information about size dependent properties in monolithic materials, studying local variation in properties throughout a microstructure, and measuring the mechanical response of fabricated structures that have small dimensions.
In 2004, a study reported on the flow behavior of micro-scale metallic samples tested in compression using a nanoindenter equipped with a flat tip diamond indenter. The lateral stiffness in these systems was fixed at a value near 0.01 N/μm. Cylindrical specimens were machined using a focused ion beam (FIB) instrument, and tests were conducted under uniaxial loading conditions similar to those practiced at the bulk scale. These ex-situ micro-scale tests are affected by some of the same undesired influences as experienced in bulk compression tests. One such influence is the platen-sample friction for which there has been no attempt to address in the micro-scale tests. The importance of frictional forces on compression testing of single crystals was first noted in 1926 where both flow stress properties and local physical sample deformation were greatly influenced by the addition of a lubricant to the platen-sample interface.
There exists a need for a system and method that enables testing of microsized samples by introducing variable lateral constraints imposed by the lateral stiffness of the testing device.